The present invention relates to a blood pressure monitor and pulse wave detection apparatus.
Blood pressure is commonly measured by auscultation which consists of applying a pressing force greater than the maximum blood pressure to the artery by pressing the brachium or wrist around the circumference and detecting a vibration of the pressed artery on the peripheral side, while gradually decreasing the pressing force.
A blood pressure monitor disclosed in Japanese Patent No. 2804484, for example, has a means of detecting displacement of the cuff for applying pressure around the wrist.
Japanese Patent Application Laid-open No. 5-300885 discloses a blood pressure monitor designed as shown in FIG. 2 of the published document, wherein the arterial blood flow is controlled by the pressing force applied to the arm by altering the degree of expansion of an air bag 7 which consists of section of a cuff wound around the arm. This pressing force is monitored by a third pressure sensor 1, which latches the pressing force when a first pressure sensor 2 detects the maximum arterial pulse wave and the pressing force when a second pressure sensor 3 detects an arterial pulse wave above a prescribed level. The peripheral blood pressure is determined based on the latched pressure information.
In these blood pressure measuring methods, however, almost the entire circumference of the brachium or wrist is pressed so that the nervous tissues which are distributed densely close to funny bones in the case of the wrist, for instance, are pressed, imparting an unpleasant and disagreeable feeling. Such an unpleasant and disagreeable feeling caused by pressing the entire circumference of the measuring section such as the extremities and fingers has been experienced when the blood pressure is measured by pressing the entire circumference of other parts such as brachium and fingers.
The present invention has been completed in view of this situation and has an object of providing a blood pressure monitor and a pulse wave detection apparatus which impart an unpleasant and disagreeable feeling to a subject only to a minimal degree.
One aspect of the present invention provides a blood pressure monitor comprising:
an artery pressing section which locally presses an artery of any one of extremities and fingers at an arbitrarily variable pressing force;
a control section which controls the pressing force applied by the artery pressing section;
a vibration sensor detecting a vibration of the artery at a point pressed by the artery pressing section or at a point peripheral to the point pressed by the artery pressing section; and
a blood pressure determination section which determines a maximum blood pressure and a minimum blood pressure based on various pressing force values applied by the artery pressing section and signals detected by the vibration sensor at the various pressing force values.
In this blood pressure monitor, the blood pressure determination section determines the maximum and minimum pressures based on various pressing force values applied when the artery pressing section locally presses an artery of the extremities or fingers and the signals detected by the vibration sensor at these various pressing force values. Because the extremities or fingers are not pressed over the entire circumference, no discomfort or unfavorable feeling will be imparted to the subject.
In addition, because the artery pressing section presses the artery only locally, the pressing operation will not be interfered with by the sinews or bones which may be present close to the artery. Therefore, the pressing operation can press the artery with certainty, ensuring measurement of the blood pressure more accurately than in the conventional method in which the entire circumference of the extremities or fingers is pressed by a cuff or the like.
Another aspect of the present invention provides a blood pressure monitor comprising:
a first artery pressing section which locally presses a first artery of any one of extremities and fingers having the first artery and a second artery at an arbitrarily variable pressing force;
a control section which controls the pressing force applied by the first artery pressing section;
a second artery pressing section which locally presses the second artery;
a vibration sensor detecting a vibration of the first artery at a pressed point or on a peripheral side thereof; and
a blood pressure determination section which determines a maximum blood pressure and a minimum blood pressure based on various pressing force values applied by the first artery pressing section and a signal detected by the vibration sensor at each of the pressing force values.
In this blood pressure monitor, the blood pressure determination section determines the maximum and minimum pressures based on various pressing force values applied when the first artery pressing section locally presses an artery of the extremities or fingers and the signals detected by the vibration sensor at these various pressing force values. Because the extremities or fingers are not pressed over the entire circumference, no discomfort or unfavorable feeling will be imparted to the subject.
In addition, because this blood pressure monitor is equipped with the second artery pressing section which locally presses the second artery, the monitor can shut off the blood flow to the peripheral side from the pressed point. Therefore, the vibration of the first artery detected by the vibration sensor will not be affected by the pulses due to the blood flowing from the second artery via the artery which connect the second and first arteries, thereby ensuring more accurate blood pressure measurement.
The above-mentioned blood pressure monitor may further comprise a positioning mechanism which positions the first pressing section and the vibration sensor on the artery.
Such a positioning mechanism ensures easy determination of positioning for the artery pressing section and the vibration sensor on the artery.
The above-mentioned blood pressure monitor may further comprise guides provided on each side of the vibration sensor and guiding the vibration sensor to the artery by being located on both sides of the artery.
This configuration ensures easy and certain positioning of the vibration sensor on the artery by causing the guides which guide the vibration sensor on the artery to be located on each side of the artery.
The above-mentioned blood pressure monitor may further comprise a peripheral side pressing section which presses the artery at a point peripheral to the vibration sensor and almost completely shuts off the vibration transmitted by an artery section peripheral to the vibration sensor.
According to this configuration, because the artery is pressed by the peripheral side pressing section on the peripheral side from the artery pressing section and the vibration sensor, pulses transmitted from branch passages of arteries or the like can be shut off, enabling mere accurate blood pressure measurement.
In the above-mentioned blood pressure monitor, it is preferable that the vibration sensor detects the vibration transmitted to the artery pressing section.
The blood pressure can be measured without causing the oscillatory sensor to directly come into contact with the skin.
The above-mentioned blood pressure monitor may further comprise a sensor pressing section which causes the vibration sensor to press the artery.
This configuration, which enables the sensor pressing section of the vibration sensor to press the artery, causes the vibration sensor to press the artery at an appropriate pressure so that a vibration from the artery can be detected with certainty.
In the above-mentioned blood pressure monitor, the vibration sensor may be a pulse wave sensor detecting a pulse waveform, and
the blood pressure monitor may further comprise a conversion section which converts the pulse waveform into a blood pressure waveform based on the maximum blood pressure and the minimum blood pressure.
In this blood pressure monitor, the conversion section converts the pulse waveforms obtained from a pulse wave detection apparatus located on the artery into blood pressure waveforms based on the maximum and minimum blood pressures measured by the blood pressure monitor, thereby obtaining blood pressure waveforms. Therefore, blood pressure waveforms can be obtained non-invasively.
The above-mentioned blood pressure monitor may further comprise a blood-pressure-waveform processing section which calculates at least one of following items based on the blood pressure waveform obtained by the conversion section; a mean blood pressure, a pulse pressure which is a difference between the maximum blood pressure and the minimum blood pressure, a after-ejection pressure which is a pressure difference between a dicrotic notch and the maximum blood pressure, a dicrotic wave height which is a pressure difference between the dicrotic notch and a dicrotic wave peak, an after-ejection pressure ratio which is the after-ejection pressure normalized by the pulse pressure, a dicrotic wave height ratio which is the dicrotic wave height normalized by the pulse pressure, and a dicrotic wave height after-ejection pressure ratio which is a ratio of the dicrotic wave height and the after-ejection pressure.
In this manner, at least one of the mean blood pressure, pulse pressure which is the difference between the maximum and minimum blood pressures, after-ejection pressure which is the pressure difference between a dicrotic notch and the maximum blood pressure, dicrotic wave height which is the pressure difference between the dicrotic notch and the dicrotic wave peak, after-ejection pressure ratio which is the after-ejection pressure normalized by the pulse pressure, and dicrotic wave height after-ejection pressure ratio which is a ratio of the dicrotic wave height and the after-ejection pressure can be calculated by the blood-pressure-waveform processing section.
In the above-mentioned blood pressure monitor, the artery pressed by the artery pressing section, of which vibration is detected by the vibration sensor, may be a radial artery.
Because the blood pressure monitor can measure blood pressure without pressing section of the wrist around the ulna in which many nerve tissues are present, it is possible to measure the blood pressure on the wrist without imparting an unpleasant and disagreeable feeling to a subject.
A pulse wave detection apparatus which is further aspect of the present invention comprises:
an artery pressing section which locally presses an artery of any one of extremities and fingers at an arbitrarily variable pressing force;
a control section which controls the pressing force applied by the artery pressing section; and
a pulse sensor detecting pulse of the artery at a pressed point or on a peripheral side thereof.
In this pulse wave detection apparatus, the pulse wave sensor detects pulse waves at the point of the artery pressing section or on the peripheral side based on variable pressing force values applied when the artery pressing section locally presses the artery of the extremities or fingers. Therefore, pulse waves at various pressures applied by the artery pressing section can be detected.
The above-mentioned pulse wave detection apparatus may further comprise a positioning mechanism which positions the artery pressing section and the pulse sensor on the artery.
Such a positioning mechanism ensures easy determination of positioning for the artery pressing section and the vibration sensor on the artery.
The above-mentioned pulse wave detection apparatus may further comprise guides provided on each side of the pulse sensor and guiding the pulse sensor to the artery by being located on both sides of the artery.
This configuration ensures easy and certain positioning of the pulse detector on the artery by causing the guides which guide the pulse detector on the artery to be located on each side of the artery.
In the above-mentioned pulse wave detection apparatus, the pulse sensor may detect the vibration transmitted to the artery pressing section.
This configuration enables the pulse detector to detect pulse waves without applying pressure to the artery from above the skin.
The above-mentioned pulse wave detection apparatus may further comprise a sensor pressing section which causes the pulse sensor to press the artery.
This configuration, which enables the sensor pressing section of the pulse detector to press the artery, causes the pulse detector to press the artery at an appropriate pressure so that pulses from the artery can be detected with certainty.
In the above-mentioned pulse wave detection apparatus, the artery pressed by the artery pressing section, of which pulse is detected by the pulse sensor, may be a radial artery.
Therefore, pulse waves from the radial artery at various pressures applied by the artery pressing section can be detected
The above-mentioned pulse wave detection apparatus may further comprise:
a pressure waveform processing section which calculates at least one of the following items based on the pulse waveform obtained by the pulse sensor:
an after-ejection pressure ratio which is an after-ejection pressure normalized by a pulse pressure, the after-ejection pressure being a pressure difference between a dicrotic notch and a maximum blood pressure, the pulse pressure being a difference between the maximum blood pressure and a minimum blood pressure;
a dicrotic notch difference ratio which is a dicrotic notch difference normalized by the pulse pressure, the dicrotic notch difference being a difference between a blood pressure of the dicrotic notch and the minimum blood pressure;
a mean-blood-pressure pulse-pressure ratio which is a ratio of the mean-blood-pressure and the pulse pressure, a dicrotic wave height ratio which is a dicrotic wave height normalized by the pulse pressure; and
a dicrotic-wave-height after-ejection pressure ratio which is a ratio of the dicrotic wave height and the after-ejection pressure.
A still further aspect of the present invention provides a blood pressure monitor comprising:
a band wound around any one of extremities and fingers;
a pressure applying section which is installed on a inner surface of the band and applies a variable pressure around any one of the extremities and fingers by changing a volume of a fluid included therein;
an artery pressing section which is attached to the pressure applying section and locally presses an artery of any one of the extremities and fingers;
a control section which controls a pressing force applied to the artery by the artery pressing section by changing the pressure applied by the pressure applying section;
a pressure sensor which detects a vibration of the artery transmitted as a pressure change of the fluid, the vibration transmitted to the fluid via the artery pressing section and the pressure applying section; and
a blood pressure determination section which determines a maximum blood pressure and a minimum blood pressure based on various pressing force values applied by the artery pressing section and a signal detected by the pressure sensor at each of the pressing force values.
In this blood pressure monitor, the artery pressing section installed in the pressure applying section located inside the band locally presses the artery at various pressures. The blood pressure determination section determines the maximum and minimum pressures based on the various pressing force values applied and the signals detected by the pressure sensor at these various pressing force values. Therefore, the artery is pressed by the artery pressing section at a sufficient pressure so that the region in which the pressure applying section or the band come into contact may not become so large. As a result, a pressure sufficiently great as to impart an unpleasant or disagreeable feeling to the subject will not be applied.
In addition, because the artery pressing section presses the artery only locally, the pressing operation will not be interfered with by the sinews or bones which may be present close to the artery. Therefore, the pressing operation can press the artery with certainty, ensuring measurement of the blood pressure more accurately than in the conventional method in which the artery is directly pressed by a cuff or the like applied to the circumference of the extremities or fingers Thus, more accurate blood pressure measurement can be ensured.
A still further aspect of the present invention provides a blood pressure monitor comprising:
a band wound around any one of extremities and fingers having a first artery and a second artery;
a pressure applying section which is installed on a inner surface of the band and applies a variable pressing force to the first artery by changing a volume of a fluid included therein;
a second artery pressing section which is attached to the pressure applying section and locally presses the second artery;
a control section which controls the pressure applied by the pressure applying section;
a pressure sensor which detects a vibration of the artery transmitted as a pressure change of the fluid via the pressure applying section; and
a blood pressure determination section which determines a maximum blood pressure and a minimum blood pressure based on various pressing force values applied by the pressure applying section and a signal detected by the pressure sensor at each of the pressing force values.
Because this blood pressure monitor is equipped with the second artery pressing section which locally presses the second artery, the monitor can shut off the blood flow to the peripheral side from the pressed point. Therefore, the signals from the first artery detected by the pressure sensor will not be affected by the pulses due to the blood flowing from the second artery via the artery which connect the second and first arteries, thereby ensuring more accurate blood pressure measurement.
In addition, because the second artery pressing section locally presses the second artery, there will be no risk of nerves or the like around the second artery being strongly pressed, thus minimizing any unpleasant or disagreeable feeling imparted to the subject.
A still further aspect of the present invention provides a blood pressure monitor comprising:
a band wound around any one of extremities and fingers having a first artery and a second artery;
a first artery pressing section which is installed on a inner surface of the band and locally applies a variable pressing force to the first artery by changing a volume of a fluid included therein;
a second artery pressing section which is installed on a inner surface of the band and locally applies a variable pressing force to the second artery by changing a volume of a fluid included therein;
a control section which controls the pressing force applied by the first artery pressing section;
a pressure sensor which detects a vibration of the artery transmitted as a pressure change of the fluid via the first artery pressing section; and
a blood pressure determination section which determines a maximum blood pressure and a minimum blood pressure based on various pressing force values applied by the first artery pressing section and a signal detected by the pressure sensor at each of the pressing force values.
In this blood pressure monitor, the first artery pressing section installed in the band locally presses the first artery at various pressures. The blood pressure determination section determines the maximum and minimum pressures based on the various pressing force values applied and the signals detected by the pressure sensor at these various pressing force values. Because the extremities or fingers are not pressed over the entire circumference by the first artery pressing section, no discomfort or unfavorable feeling will be imparted to the subject.
In addition, because this blood pressure monitor is equipped with the second artery pressing section which locally presses the second artery, the monitor can shut off the blood flow to the peripheral side from the pressed point. Therefore, the vibration from the first artery detected by the pressure sensor will not be affected by the pulses due to the blood flowing from the second artery via the artery which connect the second and first arteries, thereby ensuring more accurate blood pressure measurement.
A still further aspect of the present invention provides a blood pressure monitor comprising:
an artery pressing section which presses an artery of any one of extremities or fingers at an arbitrarily variable pressing force;
a control section which controls the pressing force applied to the artery by the artery pressing section so as to gradually increase the pressing force from a predetermined minimum pressing force;
a pressure sensor detecting a vibration of the artery at a point pressed by the artery pressing section or at a point peripheral to the point pressed by the artery pressing section; and
a blood pressure determination section which determines a maximum blood pressure and a minimum blood pressure based on various pressing force values applied by the artery pressing section and a signal detected by the pressure sensor at each of the pressing force values.
According to this blood pressure monitor, the control section controls the pressure applied to the artery by the artery pressing section so that this pressure may be gradually increased from the prescribed minimum pressure. The blood pressure is measured based on the signals detected by the pressure sensor and the pressure applied at the point of measurement. The blood pressure is determined according to the same principle of the auscultation method using this blood pressure monitor. Specifically, a vibration of blood vessel walls due to blood flowing through the blood vessel constricted by the pressure applied on the peripheral side of the artery is monitored while changing the pressure applied by the artery. The blood pressure is then determined from the highest pressure of the artery pressing section detected by the vibration sensor which detects a vibration of the blood flowing through the constricted blood vessels as the maximum blood pressure, and the lowest pressure of the artery pressing section detected by the vibration sensor which detects a vibration of the blood flowing through the constricted blood vessels as the minimum blood pressure. In the blood pressure measurement using this blood pressure monitor, because the pressure applied by the pressure applying section is gradually increased starting from a pressure lower than the conceivable lowest pressure (the prescribed minimum value), the pressure measurement operation is completed when the pressure of the artery pressing section becomes almost equivalent to a pressure corresponding the maximum pressure. Therefore, the maximum pressure applied to the artery pressing section can be decreased using this blood pressure monitor as compared with conventional blood pressure monitors in which a pressure higher than the conceivable maximum pressure is first applied and then gradually decreased. As a result, a pressure sufficiently great as to impart an unpleasant or disagreeable feeling to the subject will not be applied.
The above-mentioned blood pressure monitor may further comprise a conversion section which converts a signal detected by the pressure sensor into a blood pressure waveform based on the maximum blood pressure and the minimum blood pressure.
In the blood pressure monitor, the blood pressure waveforms can be obtained from the conversion section which converts the signals detected by the pressure sensor based on the maximum and minimum blood pressure. Therefore, blood pressure waveforms can be obtained non-invasively.
The above-mentioned blood pressure monitor may further comprise a blood-pressure-waveform processing section which calculates at least one of following items based on the blood pressure waveform obtained by the conversion section: a mean blood pressure, a pulse pressure which is a difference between the maximum blood pressure and the minimum blood pressure, an after-ejection pressure which is a pressure difference between a dicrotic notch and the maximum blood pressure, a dicrotic wave height which is a pressure difference between the dicrotic notch and a dicrotic wave peak, an after-ejection pressure ratio which is the after-ejection pressure normalized by the pulse pressure, a dicrotic wave height ratio which is the dicrotic wave height normalized by the pulse pressure, and a dicrotic wave height after-ejection pressure ratio which is a ratio of the dicrotic wave height and the after-ejection pressure.
In this manner, at least one of the mean blood pressure, pulse pressure which is the difference between the maximum and minimum blood pressures, after-ejection pressure which is the pressure difference between a dicrotic notch and the maximum blood pressure, dicrotic wave height which is the pressure difference between the dicrotic notch and the dicrotic wave peak, after-ejection pressure ratio which is the after-ejection pressure normalized by the pulse pressure, and dicrotic wave height after-ejection pressure ratio which is a ratio of the is dicrotic wave height and the after-ejection pressure can be calculated by the blood-pressure-waveform processing section.